My invention relates to an arrangement for controlling the volume or other operating characteristic of radio apparatus or the like. My invention particularly relates to such an arrangement that permits a single manual device to select the volume or other operating characteristic for each of a plurality of operating modes of the radio, and that provides the selected volume or other operating characteristic when the respective mode is selected again.
Radio and electronic apparatus often require a number of control functions, each of which requires an individual knob or control. If there are many such functions, the number of knobs or controls becomes unacceptable. This is particularly true of relatively small apparatus, such as the control head or operator console for a vehicular or mobile radiotelephone. Such a mobile radiotelephone requires three different volume controls: the first control sets the alert or ringing tone volume for the radiotelephone; the second control sets the audio loudspeaker volume for the radiotelephone; and the third control sets the audio handset volume for the radiotelephone. At the present time, these three needed volume controls require three separate knobs or adjusting means in order that the three volumes can be set and maintained independently. Such independent settings are desirable or in some cases necessary where a user wants one volume level for the ringing or alert signals, another volume level for the audio output from the loudspeaker, and still another volume level for the audio output from the handset. In addition, it is desirable or necessary that each volume level be set or determined when in use without affecting the other volume settings. Three separate knobs to meet these requirements make it difficult and confusing for a user to select the correct knob or control that adjusts the alert volume output, or the loudspeaker volume output, or the handset volume output. Furthermore, the three separate knobs require a large physical space and are expensive.